The present invention relates generally to portable optical scanners and more specifically to rollers for use in portable optical scanners.
Portable optical scanners convert graphical and textual information on a printed page, a photograph, and the like into digital information for use by computers. To capture an image, a user passes a portable optical scanner over the surface of the image to be scanned. A special reading head associated with the scanner scans the image and converts the light reflected from the image into digital information. Rollers in the scanner maintain a relatively constant gap between the reading head and the scanned surface, and permit the scanner to be rolled instead of dragged across the scanned surface. The digital information from the scanner's reading head is then manipulated to reconstruct a digital representation of the scanned image. The digital representation of the image can then be manipulated, stored, or utilized.
Because portable optical scanners are designed to be relatively compact, there will be situations where the size of the image to be scanned exceeds the width of the reading head. To capture the entire image using a portable optical scanner, the user must capture the image portion by portion by making multiple passes with the scanner over the surface of the area to be scanned. Each pass captures a strip of the area to be scanned. Special software is then used to assemble the various scanned strips and to reconstruct a digital image of the entire scanned area.
Some times, the area to be scanned may be a single column of text or newsprint. In this situation, the portable optical scanner may be utilized to capture the column of text by making a single pass down the column. If the scanner is rolled straight down the column, the desired column or strip is captured. If the scanner swerves off the desired strip or column even momentarily, a portion of the area to be captured may be lost.
There is desired an improved roller which permits a portable optical scanner to roll freely over a scanned surface in a linear manner. The improved roller should resist any weaving motion of the portable optical scanner in any direction other than the desired straight-line direction. The improved roller should be relatively lightweight and inexpensive to manufacture. Such an improved roller would materially improves the utility of the portable optical scanners and the quality of the digital image.